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There are smart ways to overhaul trains and buses, and not-so-smart.

If anything good comes out of the current arms race between North American cities to land Amazon’s second headquarters, it might be a disruption of one of the more intractable subjects of public discourse: mass transportation.

Direct access to rail, train, subway and bus routes was chief among Amazon’s requirements in the request-for-proposals it issued to cities nationwide in search of its second headquarters. As readers may by now be sick of hearing, the colossus of e-commerce is promising bidders 50,000 new jobs with average salaries of $100,000, plus $5 billion of investments: a siren’s song to cash-hungry and not-so-cash-hungry metros alike. Cities are now jousting thirstily for Amazon’s attention, a spectacle that has been at turns entertaining, embarrassing, and legitimately provocative.

The emphasis on transit seems to be creating, in particular, something of a come-to-Jesus moment for cities where high-level service has long been an afterthought. Cities with legacy subway systems, such as Boston and Washington, D.C., have risen to the top of more than one ranking; so has Denver, with its relatively forgiving traffic and expanded rail investments. In weeks of speculation and showdowns, a lack of transit connectivity has been one of the the great presumed disqualifiers for other towns.

Look at how folks putting together Raleigh, North Carolina’s proposal are talking about themselves. Raleigh is home to the so-called “Triangle,” a phalanx of research institutions chock-full of human capital. “I felt like the region performed strongly on all of the criteria,” Michael Pittman, vice-president for marketing and communications at the Research Triangle Foundation, told the News & Observer. “And then you get to transit and you think, well that might be our weakness. Because we don’t have a mass transit system in place yet.”

Atlanta is another leading contender. Its massive international air hub and low cost of living make it stand out. But so does its paralyzing traffic and lack of reliable transit. If Amazon is serious about replicating the sort of urban campus model it’s established in Seattle, the Big Peach might be a long shot. “There’s nothing like being left out of the money to force a rethinking of policy,” wrote the Atlanta Journal-Constitution’s Jim Galloway, reporting on a meeting between Georgia Governor Nathan Deal and regional leaders over concerns that Atlanta would be eliminated over its dysfunctional local transportation systems.

I can’t imagine Amazon is dumb enough to be fooled by those kind of booster stats that don’t mean anything when it comes down to the messy business of actually moving people around a city. And as anyone who has ever dealt with DART knows, Dallas-area public transit is terrible at moving people around the city efficiently.

Leaders of car-oriented cities around the country might be ogling some of the shiny new mass transit systems in the country and wondering how they might build one of their own. (Or, in the case of Baltimore, whose $3 billion crosstown light-rail project was scuttled in 2015, ruefully regretting recent missed opportunities.) But they should be careful. Building effective mass transport—presumably, the kind Amazon is interested in—is not the same as building trains. Cities might look to Seattle, the city where Amazon already lives, to reverse-engineer their way to HQ2-style mobility.

In order to manage congestion and growth on local streets, the country’s biggest company town has adopted a transit plan that ensures priorities are attuned to local needs, rather than rely solely on its regional transit agency for vision. Notably, Seattle has placed an emphasis on improving the bus network, “systematically rethinking its bus routes one quadrant of the city at a time,” according to StreetsBlog—a bet that’s mostly paid off. Meanwhile, it’s pouring billions into a light-rail expansion. Focused attention on frequent, well-connected service are why, experts say, Seattle is one of vanishingly few U.S. cities where transit ridership is actually increasing.

Somewhat unexpectedly, another one is Houston, which also recently revamped its poorly performing bus network with an emphasis on density and frequency over geographic spread. But the Texas metro has been DQed by many speculators for its lack of highly skilled labor and still-scant transit resources.

With ultra-high costs of living in HQ2 contenders like Boston and Washington, D.C., Denver has emerged on the top of the heap in many speculative shortlists. On top of its highly educated workforce and logistical assets as an air and highway hub, the Colorado city has an $8 billion plan to spread 121 miles of hub-and-spoke light and commuter rail tracks around the metro area. The 23-mile A-train to Denver International, which opened in 2016, is a clear sign to visitors that it’s serious about transit.

But for residents in city limits, the regional approach to transit hasn’t yet served them particularly well. High-frequency, cross-town connections by bus or rail are still lacking. And though the number of riders on Denver’s transit network has grown, the share has not. In fact, ridership fell 1.2 percent last year.

It’s still early days in Denver, but it’s not so early in L.A., which has been building out a hub-and-spoke metro system for years, mostly with an emphasis on wide geographic coverage. The county has long devoted far fewer resources to maintaining frequency or speed on its buses, which serve the vast majority of riders. Overall, system ridership has been declining, steadily, since 2014. (Low gas prices don’t help.)

Whatever city Amazon chooses may pledge to adjust its transportation infrastructure to better serve the retail behemoth’s needs. Their first instinct probably won’t be to shine up their grubby old buses. Subways and light rail looks better, like it would draw suburban commuters out of their cars. But that’s a bias that might get them in trouble. Transit investments that don’t support people who already ride transit rarely deliver meaningful ridership gains. For cities pencilling out tax-abatement courtship plans, eager for Amazon’s huge investment, this a lesson in miniature: If those bids undermine the lives of people already living there, the attraction might be fatal.